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Hypothyroidism: Signs and Symptoms for Adults, Teens, and Infants

Hypothyroidism: Signs and Symptoms for Adults, Teens, and Infants

Hypothyroidism, also called underactive thyroid disease, occurs when there is a low-level production of thyroid hormones. Thyroid hormones are responsible for the regulation of a stable metabolism. An underactive thyroid may cause many health problems, leading to severe complications and death if left untreated.

Hypothyroidism is more common in women than men. It especially occurs between ages 35 and 65. However, most women are not aware of their condition due to the complicated symptoms that hypothyroidism presents.

Causes of hypothyroidism

Hypothyroidism has two categories, primary and secondary. The difference between these two is their causes.

Primary hypothyroidism occurs due to thyroid gland destruction, such as in the following cases:

  • Hashimoto’s disease
  • Iodine deficiency
  • Radioiodine treatment
  • Medications, like amiodarone, bexarotene, ethionamide, and phenobarbital
  • Head and neck area radiation therapy

Secondary or central hypothyroidism is related to hypothalamic-pituitary axis defects, which are defects in the part of the neuroendocrine system that is responsible for regulating metabolism.

  • Pituitary tumors
  • Sheehan syndrome
  • Resistance to thyroid releasing hormone (TRH)
  • Thyroid releasing hormone (TRH) deficiency
  • Brain radiation therapy
  • Medications, such as dopamine and prednisone
  • Inflammation of the pituitary gland

Signs and symptoms of hypothyroidism

The signs and symptoms of hypothyroidism may vary depending on age and gender. Some symptoms also occur based on the severity of the disease. In most cases, symptoms are difficult to recognize as hypothyroidism.

Symptoms for adults and teens:

  • Feeling tired
  • Coldness intolerance
  • Weight gain
  • Puffy face
  • Dry skin
  • Voice hoarseness
  • Hair loss
  • High blood cholesterol level
  • Muscle and joint aches, swelling, and stiffness
  • Depression
  • Unusual heavy or irregular menstruation period
  • Unusual forgetfulness

Other symptoms for teens:

  • Short height due to delay growth development
  • Delay in permanent teeth development
  • Delayed puberty

Symptoms for babies or infants:

  • Large, projecting tongue
  • Yellow skin and eyes, called jaundice
  • Difficulty in breathing
  • Crying with hoarseness
  • Umbilical hernia
  • Constipation
  • Too much sleep
  • Floppy muscles

Risk factors

Any gender and age can have hypothyroidism, but here are some potential factors that increase the risk of developing one.

  • Is a woman
  • Elderly, ages beyond 60
  • Existing autoimmune disease
  • Family history of thyroid disease
  • Partial thyroidectomy
  • Mothers who have been pregnant and delivered a baby


If hypothyroidism is left untreated for a long time, it may lead to severe complications, including the following:


This is an enlargement and swelling of the thyroid that causes a lump on the neck. It may also affect your physical appearance and cause difficulty while eating.

Heart disease

A defect in thyroid gland hormone production increases cholesterol levels. This cholesterol may cause heart disease, and may even lead to a heart attack, as it blocks the blood flow in the artery.

Birth problems

Pregnant women with untreated hypothyroidism are at risk of premature birth, miscarriage, and loss of a baby during delivery. Their babies are also at risk for having intellectual problems and poor development.


Low thyroid hormones affect the chances of women getting pregnant. This is due to difficulty in releasing the egg from the ovary.


Hypothyroidism can worsen depression, until it gets treated.

Myxedema coma

This is a rare complication that occurs from severe hypothyroidism that is left untreated. It results in a poor mental state, hypothermia, respiratory failure, and cardiogenic shock.

Diagnosing hypothyroidism

Doctors perform a physical exam to check for signs and symptoms. They may also require a blood test to screen the body’s levels of thyroid-stimulating hormone (TSH) and thyroid thyroxine (T4).


The standard treatment for hypothyroidism is levothyroxine monotherapy. This treatment aims to replace the T4 that the thyroid does not produce anymore.

The dosage of the medication depends on the patient’s weight and condition. The dosage may be adjusted following a blood test and screening for thyroid hormones. Follow-up blood tests may occur after six months, and annually thereafter.

Key takeaway

Hypothyroidism is a common disease, especially among women. It refers to an underactive thyroid gland. Many patients do not realize that they have this condition because of little or no symptoms. In most cases, symptoms only occur when the disease is becoming more severe. If hypothyroidism is left untreated, it may cause more life-threatening health problems. Consult a doctor once symptoms become evident.

Learn more about General Health Knowledge here.


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Written by Shienna Santelices Updated Jun 23
Fact Checked by Hello Doctor Medical Panel